From dbbae5e00e49d3a69dc10978e38299e3f28dd1e1 Mon Sep 17 00:00:00 2001 From: Pratik Naik Date: Sun, 7 Dec 2008 03:27:53 +0100 Subject: Merge with docrails --- railties/doc/guides/html/creating_plugins.html | 1312 +++++++++++++++--------- 1 file changed, 815 insertions(+), 497 deletions(-) (limited to 'railties/doc/guides/html/creating_plugins.html') diff --git a/railties/doc/guides/html/creating_plugins.html b/railties/doc/guides/html/creating_plugins.html index 375d216b4a..850822c8ed 100644 --- a/railties/doc/guides/html/creating_plugins.html +++ b/railties/doc/guides/html/creating_plugins.html @@ -199,14 +199,22 @@ ul#navMain {

Chapters

  1. - Preparation + Setup +
    2. +
  2. + Tests +
      + +
    • Test Setup
    • Run the plugin tests
      • @@ -216,16 +224,12 @@ ul#navMain { Extending core classes
    • - Add an acts_as_yaffle method to Active Record + Add an acts_as method to Active Record
    • - Create a generator - + Models
    • - Add a custom generator command + Controllers
    • - Add a model + Helpers
    • - Add a controller + Routes
    • - Add a helper + Generators +
    • - Add a Custom Route + Generator Commands
    • - Odds and ends + Migrations
    • + Rake tasks +
      • +
    • + PluginGems +
      • +
    • + RDoc Documentation +
      • +
    • Appendix @@ -388,7 +395,7 @@ A custom route method that can be used in routes.rb

      For the purpose of this guide pretend for a moment that you are an avid bird watcher. Your favorite bird is the Yaffle, and you want to create a plugin that allows other developers to share in the Yaffle goodness. First, you need to get setup for development.

      -

      1. Preparation

      +

      1. Setup

      1.1. Create the basic app

      The examples in this guide require that you have a working rails application. To create a simple rails app execute:

      @@ -447,10 +454,30 @@ create vendor/plugins/yaffle/generators/yaffle/templates create vendor/plugins/yaffle/generators/yaffle/yaffle_generator.rb create vendor/plugins/yaffle/generators/yaffle/USAGE
      -

      To begin just change one thing - move init.rb to rails/init.rb.

      -

      1.3. Setup the plugin for testing

      -

      If your plugin interacts with a database, you'll need to setup a database connection. In this guide you will learn how to test your plugin against multiple different database adapters using Active Record. This guide will not cover how to use fixtures in plugin tests.

      -

      To setup your plugin to allow for easy testing you'll need to add 3 files:

      +

      1.3. Organize your files

      +

      To make it easy to organize your files and to make the plugin more compatible with GemPlugins, start out by altering your file system to look like this:

      +
      +
      +
      |-- lib
+|   |-- yaffle
+|   `-- yaffle.rb
+`-- rails
+    |
+    `-- init.rb
      +
      +

      vendor/plugins/yaffle/rails/init.rb

      +
      +
      +
      require 'yaffle'
+
      +

      Now you can add any require statements to lib/yaffle.rb and keep init.rb clean.

      + +

      2. Tests

      +
      +

      In this guide you will learn how to test your plugin against multiple different database adapters using Active Record. To setup your plugin to allow for easy testing you'll need to add 3 files:

      • @@ -468,6 +495,7 @@ A test helper method that sets up the database

      +

      2.1. Test Setup

      vendor/plugins/yaffle/test/database.yml:

      @@ -558,7 +586,7 @@ ENV['RAILS_ROOT end

      Now whenever you write a test that requires the database, you can call load_schema.

      -

      1.4. Run the plugin tests

      +

      2.2. Run the plugin tests

      Once you have these files in place, you can write your first test to ensure that your plugin-testing setup is correct. By default rails generates a file in vendor/plugins/yaffle/test/yaffle_test.rb with a sample test. Replace the contents of that file with:

      vendor/plugins/yaffle/test/yaffle_test.rb:

      @@ -619,22 +647,9 @@ rake DB=postgresql

      Now you are ready to test-drive your plugin!

      -

      2. Extending core classes

      +

      3. Extending core classes

      -

      This section will explain how to add a method to String that will be available anywhere in your rails app by:

      -
        -
      • -

        -Writing tests for the desired behavior -

        -
        • -
      • -

        -Creating and requiring the correct files -

        -
        • -
      -

      2.1. Creating the test

      +

      This section will explain how to add a method to String that will be available anywhere in your rails app.

      In this example you will add a method to String named to_squawk. To begin, create a new test file with a few assertions:

      vendor/plugins/yaffle/test/core_ext_test.rb

      @@ -665,24 +680,6 @@ NoMethodError: undefined method `to_squawk' for "Hello World":String ./test/core_ext_test.rb:5:in `test_to_squawk_prepends_the_word_squawk'

      Great - now you are ready to start development.

      -

      2.2. Organize your files

      -

      A common pattern in rails plugins is to set up the file structure like this:

      -
      -
      -
      |-- lib
-|   |-- yaffle
-|   |   `-- core_ext.rb
-|   `-- yaffle.rb
      -
      -

      The first thing we need to to is to require our lib/yaffle.rb file from rails/init.rb:

      -

      vendor/plugins/yaffle/rails/init.rb

      -
      -
      -
      require 'yaffle'
-

      Then in lib/yaffle.rb require lib/core_ext.rb:

      vendor/plugins/yaffle/lib/yaffle.rb

      @@ -712,11 +709,11 @@ http://www.gnu.org/software/src-highlite --> >> "Hello World".to_squawk => "squawk! Hello World"
      -

      2.3. Working with init.rb

      -

      When rails loads plugins it looks for the file named init.rb. However, when the plugin is initialized, init.rb is invoked via eval (not require) so it has slightly different behavior.

      +

      3.1. Working with init.rb

      +

      When rails loads plugins it looks for the file named init.rb or rails/init.rb. However, when the plugin is initialized, init.rb is invoked via eval (not require) so it has slightly different behavior.

      Under certain circumstances if you reopen classes or modules in init.rb you may inadvertently create a new class, rather than reopening an existing class. A better alternative is to reopen the class in a different file, and require that file from init.rb, as shown above.

      If you must reopen a class in init.rb you can use module_eval or class_eval to avoid any issues:

      -

      vendor/plugins/yaffle/init.rb

      +

      vendor/plugins/yaffle/rails/init.rb

      end

      Another way is to explicitly define the top-level module space for all modules and classes, like ::Hash:

      -

      vendor/plugins/yaffle/init.rb

      +

      vendor/plugins/yaffle/rails/init.rb

      end
      -

      3. Add an acts_as_yaffle method to Active Record

      +

      4. Add an acts_as method to Active Record

      A common pattern in plugins is to add a method called acts_as_something to models. In this case, you want to write a method called acts_as_yaffle that adds a squawk method to your models.

      To begin, set up your files so that you have:

      @@ -801,7 +798,7 @@ http://www.gnu.org/software/src-highlite --> end

      With structure you can easily separate the methods that will be used for the class (like Hickwall.some_method) and the instance (like @hickwell.some_method).

      -

      3.1. Add a class method

      +

      4.1. Add a class method

      This plugin will expect that you've added a method to your model named last_squawk. However, the plugin users might have already defined a method on their model named last_squawk that they use for something else. This plugin will allow the name to be changed by adding a class method called yaffle_text_field.

      To start out, write a failing test that shows the behavior you'd like:

      vendor/plugins/yaffle/test/acts_as_yaffle_test.rb

      @@ -854,7 +851,7 @@ http://www.gnu.org/software/src-highlite --> ActiveRecord::Base.send :include, Yaffle -

      3.2. Add an instance method

      +

      4.2. Add an instance method

      This plugin will add a method named squawk to any Active Record objects that call acts_as_yaffle. The squawk method will simply set the value of one of the fields in the database.

      To start out, write a failing test that shows the behavior you'd like:

      vendor/plugins/yaffle/test/acts_as_yaffle_test.rb

      @@ -936,362 +933,104 @@ ActiveRecord::Base4. Create a generator +

      5. Models

      -

      Many plugins ship with generators. When you created the plugin above, you specified the —with-generator option, so you already have the generator stubs in vendor/plugins/yaffle/generators/yaffle.

      -

      Building generators is a complex topic unto itself and this section will cover one small aspect of generators: creating a generator that adds a time-stamped migration.

      -

      To create a generator you must:

      -
        -
      • -

        -Add your instructions to the manifest method of the generator -

        -
        • -
      • -

        -Add any necessary template files to the templates directory -

        -
        • -
      • -

        -Test the generator manually by running various combinations of script/generate and script/destroy -

        -
        • -
      • -

        -Update the USAGE file to add helpful documentation for your generator -

        -
        • -
      -

      4.1. Testing generators

      -

      Many rails plugin authors do not test their generators, however testing generators is quite simple. A typical generator test does the following:

      -
        -
      • -

        -Creates a new fake rails root directory that will serve as destination -

        -
        • -
      • -

        -Runs the generator forward and backward, making whatever assertions are necessary -

        -
        • -
      • -

        -Removes the fake rails root -

        -
        • -
      -

      For the generator in this section, the test could look something like this:

      -

      vendor/plugins/yaffle/test/yaffle_generator_test.rb

      +

      This section describes how to add a model named Woodpecker to your plugin that will behave the same as a model in your main app. When storing models, controllers, views and helpers in your plugin, it's customary to keep them in directories that match the rails directories. For this example, create a file structure like this:

      +
      +
      +
      vendor/plugins/yaffle/
+|-- lib
+|   |-- app
+|   |   |-- controllers
+|   |   |-- helpers
+|   |   |-- models
+|   |   |   `-- woodpecker.rb
+|   |   `-- views
+|   |-- yaffle
+|   |   |-- acts_as_yaffle.rb
+|   |   |-- commands.rb
+|   |   `-- core_ext.rb
+|   `-- yaffle.rb
      +
      +

      As always, start with a test:

      +

      vendor/plugins/yaffle/yaffle/woodpecker_test.rb:

      require File.dirname(__FILE__) + '/test_helper.rb'
-require 'rails_generator'
-require 'rails_generator/scripts/generate'
-require 'rails_generator/scripts/destroy'
-
-class GeneratorTest < Test::Unit::TestCase
-
-  def fake_rails_root
-    File.join(File.dirname(__FILE__), 'rails_root')
-  end
-
-  def file_list
-    Dir.glob(File.join(fake_rails_root, "db", "migrate", "*"))
-  end
-
-  def setup
-    FileUtils.mkdir_p(fake_rails_root)
-    @original_files = file_list
-  end
 
-  def teardown
-    FileUtils.rm_r(fake_rails_root)
-  end
+class WoodpeckerTest < Test::Unit::TestCase
+  load_schema
 
-  def test_generates_correct_file_name
-    Rails::Generator::Scripts::Generate.new.run(["yaffle", "bird"], :destination => fake_rails_root)
-    new_file = (file_list - @original_files).first
-    assert_match /add_yaffle_fields_to_bird/, new_file
+  def test_woodpecker
+    assert_kind_of Woodpecker, Woodpecker.new
   end
-
 end
      -

      You can run rake from the plugin directory to see this fail. Unless you are doing more advanced generator commands it typically suffices to just test the Generate script, and trust that rails will handle the Destroy and Update commands for you.

      -

      4.2. Adding to the manifest

      -

      This example will demonstrate how to use one of the built-in generator methods named migration_template to create a migration file. To start, update your generator file to look like this:

      -

      vendor/plugins/yaffle/generators/yaffle/yaffle_generator.rb

      +

      This is just a simple test to make sure the class is being loaded correctly. After watching it fail with rake, you can make it pass like so:

      +

      vendor/plugins/yaffle/lib/yaffle.rb:

      -
      class YaffleGenerator < Rails::Generator::NamedBase
-  def manifest
-    record do |m|
-      m.migration_template 'migration:migration.rb', "db/migrate", {:assigns => yaffle_local_assigns,
-        :migration_file_name => "add_yaffle_fields_to_#{custom_file_name}"
-      }
-    end
-  end
-
-  private
-    def custom_file_name
-      custom_name = class_name.underscore.downcase
-      custom_name = custom_name.pluralize if ActiveRecord::Base.pluralize_table_names
-    end
-
-    def yaffle_local_assigns
-      returning(assigns = {}) do
-        assigns[:migration_action] = "add"
-        assigns[:class_name] = "add_yaffle_fields_to_#{custom_file_name}"
-        assigns[:table_name] = custom_file_name
-        assigns[:attributes] = [Rails::Generator::GeneratedAttribute.new("last_squawk", "string")]
-      end
-    end
+
      %w{ models }.each do |dir|
+  path = File.join(File.dirname(__FILE__), 'app', dir)
+  $LOAD_PATH << path
+  ActiveSupport::Dependencies.load_paths << path
+  ActiveSupport::Dependencies.load_once_paths.delete(path)
 end
      -

      The generator creates a new file in db/migrate with a timestamp and an add_column statement. It reuses the built in rails migration_template method, and reuses the built-in rails migration template.

      -

      It's courteous to check to see if table names are being pluralized whenever you create a generator that needs to be aware of table names. This way people using your generator won't have to manually change the generated files if they've turned pluralization off.

      -

      4.3. Manually test the generator

      -

      To run the generator, type the following at the command line:

      -
      -
      -
      ./script/generate yaffle bird
      -
      -

      and you will see a new file:

      -

      db/migrate/20080529225649_add_yaffle_fields_to_birds.rb

      +

      Adding directories to the load path makes them appear just like files in the the main app directory - except that they are only loaded once, so you have to restart the web server to see the changes in the browser. Removing directories from the load_once_paths allow those changes to picked up as soon as you save the file - without having to restart the web server. This is particularly useful as you develop the plugin.

      +

      vendor/plugins/yaffle/lib/app/models/woodpecker.rb:

      -
      class AddYaffleFieldsToBirds < ActiveRecord::Migration
-  def self.up
-    add_column :birds, :last_squawk, :string
-  end
-
-  def self.down
-    remove_column :birds, :last_squawk
-  end
+
      class Woodpecker < ActiveRecord::Base
 end
      -

      4.4. The USAGE file

      -

      Rails ships with several built-in generators. You can see all of the generators available to you by typing the following at the command line:

      -
      -
      -
      script/generate
      -
      -

      You should see something like this:

      -
      -
      -
      Installed Generators
-  Plugins (vendor/plugins): yaffle
-  Builtin: controller, integration_test, mailer, migration, model, observer, plugin, resource, scaffold, session_migration
      -
      -

      When you run script/generate yaffle you should see the contents of your vendor/plugins/yaffle/generators/yaffle/USAGE file.

      -

      For this plugin, update the USAGE file looks like this:

      -
      -
      -
      Description:
-    Creates a migration that adds yaffle squawk fields to the given model
-
-Example:
-    ./script/generate yaffle hickwall
-
-    This will create:
-        db/migrate/TIMESTAMP_add_yaffle_fields_to_hickwall
      -
      -
      -

      5. Add a custom generator command

      -
      -

      You may have noticed above that you can used one of the built-in rails migration commands migration_template. If your plugin needs to add and remove lines of text from existing files you will need to write your own generator methods.

      -

      This section describes how you you can create your own commands to add and remove a line of text from routes.rb. This example creates a very simple method that adds or removes a text file.

      -

      To start, add the following test method:

      -

      vendor/plugins/yaffle/test/generator_test.rb

      +

      Finally, add the following to your plugin's schema.rb:

      +

      vendor/plugins/yaffle/test/schema.rb:

      -
      def test_generates_definition
-  Rails::Generator::Scripts::Generate.new.run(["yaffle", "bird"], :destination => fake_rails_root)
-  definition = File.read(File.join(fake_rails_root, "definition.txt"))
-  assert_match /Yaffle\:/, definition
+
      create_table :woodpeckers, :force => true do |t|
+  t.string :name
 end
      -

      Run rake to watch the test fail, then make the test pass add the following:

      -

      vendor/plugins/yaffle/generators/yaffle/templates/definition.txt

      -
      -
      -
      Yaffle: A bird
      -
      -

      vendor/plugins/yaffle/lib/yaffle.rb

      -
      -
      -
      require "yaffle/commands"
-
      -

      vendor/plugins/yaffle/lib/commands.rb

      +

      Now your test should be passing, and you should be able to use the Woodpecker model from within your rails app, and any changes made to it are reflected immediately when running in development mode.

      +
      +

      6. Controllers

      +
      +

      This section describes how to add a controller named woodpeckers to your plugin that will behave the same as a controller in your main app. This is very similar to adding a model.

      +

      You can test your plugin's controller as you would test any other controller:

      +

      vendor/plugins/yaffle/test/woodpeckers_controller_test.rb:

      -
      require 'rails_generator'
-require 'rails_generator/commands'
+
      require File.dirname(__FILE__) + '/test_helper.rb'
+require 'woodpeckers_controller'
+require 'action_controller/test_process'
 
-module Yaffle #:nodoc:
-  module Generator #:nodoc:
-    module Commands #:nodoc:
-      module Create
-        def yaffle_definition
-          file("definition.txt", "definition.txt")
-        end
-      end
-
-      module Destroy
-        def yaffle_definition
-          file("definition.txt", "definition.txt")
-        end
-      end
-
-      module List
-        def yaffle_definition
-          file("definition.txt", "definition.txt")
-        end
-      end
-
-      module Update
-        def yaffle_definition
-          file("definition.txt", "definition.txt")
-        end
-      end
-    end
-  end
-end
-
-Rails::Generator::Commands::Create.send   :include,  Yaffle::Generator::Commands::Create
-Rails::Generator::Commands::Destroy.send  :include,  Yaffle::Generator::Commands::Destroy
-Rails::Generator::Commands::List.send     :include,  Yaffle::Generator::Commands::List
-Rails::Generator::Commands::Update.send   :include,  Yaffle::Generator::Commands::Update
-
      -

      Finally, call your new method in the manifest:

      -

      vendor/plugins/yaffle/generators/yaffle/yaffle_generator.rb

      -
      -
      -
      class YaffleGenerator < Rails::Generator::NamedBase
-  def manifest
-    m.yaffle_definition
-  end
-end
-
      -
      -

      6. Add a model

      -
      -

      This section describes how to add a model named Woodpecker to your plugin that will behave the same as a model in your main app. When storing models, controllers, views and helpers in your plugin, it's customary to keep them in directories that match the rails directories. For this example, create a file structure like this:

      -
      -
      -
      vendor/plugins/yaffle/
-|-- lib
-|   |-- app
-|   |   |-- controllers
-|   |   |-- helpers
-|   |   |-- models
-|   |   |   `-- woodpecker.rb
-|   |   `-- views
-|   |-- yaffle
-|   |   |-- acts_as_yaffle.rb
-|   |   |-- commands.rb
-|   |   `-- core_ext.rb
-|   `-- yaffle.rb
      -
      -

      As always, start with a test:

      -

      vendor/plugins/yaffle/yaffle/woodpecker_test.rb:

      -
      -
      -
      require File.dirname(__FILE__) + '/test_helper.rb'
-
-class WoodpeckerTest < Test::Unit::TestCase
-  load_schema
-
-  def test_woodpecker
-    assert_kind_of Woodpecker, Woodpecker.new
-  end
-end
-
      -

      This is just a simple test to make sure the class is being loaded correctly. After watching it fail with rake, you can make it pass like so:

      -

      vendor/plugins/yaffle/lib/yaffle.rb:

      -
      -
      -
      %w{ models }.each do |dir|
-  path = File.join(File.dirname(__FILE__), 'app', dir)
-  $LOAD_PATH << path
-  ActiveSupport::Dependencies.load_paths << path
-  ActiveSupport::Dependencies.load_once_paths.delete(path)
-end
-
      -

      Adding directories to the load path makes them appear just like files in the the main app directory - except that they are only loaded once, so you have to restart the web server to see the changes in the browser. Removing directories from the load_once_paths allow those changes to picked up as soon as you save the file - without having to restart the web server. This is particularly useful as you develop the plugin.

      -

      vendor/plugins/yaffle/lib/app/models/woodpecker.rb:

      -
      -
      -
      class Woodpecker < ActiveRecord::Base
-end
-
      -

      Finally, add the following to your plugin's schema.rb:

      -

      vendor/plugins/yaffle/test/schema.rb:

      -
      -
      -
      ActiveRecord::Schema.define(:version => 0) do
-  create_table :woodpeckers, :force => true do |t|
-    t.string :name
-  end
-end
-
      -

      Now your test should be passing, and you should be able to use the Woodpecker model from within your rails app, and any changes made to it are reflected immediately when running in development mode.

      -
      -

      7. Add a controller

      -
      -

      This section describes how to add a controller named woodpeckers to your plugin that will behave the same as a controller in your main app. This is very similar to adding a model.

      -

      You can test your plugin's controller as you would test any other controller:

      -

      vendor/plugins/yaffle/yaffle/woodpeckers_controller_test.rb:

      -
      -
      -
      require File.dirname(__FILE__) + '/test_helper.rb'
-require 'woodpeckers_controller'
-require 'action_controller/test_process'
-
-class WoodpeckersController; def rescue_action(e) raise e end; end
+class WoodpeckersController; def rescue_action(e) raise e end; end
 
 class WoodpeckersControllerTest < Test::Unit::TestCase
   def setup
     @controller = WoodpeckersController.new
     @request = ActionController::TestRequest.new
     @response = ActionController::TestResponse.new
+
+    ActionController::Routing::Routes.draw do |map|
+      map.resources :woodpeckers
+    end
   end
 
   def test_index
@@ -1330,7 +1069,7 @@ http://www.gnu.org/software/src-highlite -->

      Now your test should be passing, and you should be able to use the Woodpeckers controller in your app. If you add a route for the woodpeckers controller you can start up your server and go to http://localhost:3000/woodpeckers to see your controller in action.

      -

      8. Add a helper

      +

      7. Helpers

      This section describes how to add a helper named WoodpeckersHelper to your plugin that will behave the same as a helper in your main app. This is very similar to adding a model and a controller.

      You can test your plugin's helper as you would test any other helper:

      @@ -1362,8 +1101,6 @@ http://www.gnu.org/software/src-highlite --> ActiveSupport::Dependencies.load_paths << path ActiveSupport::Dependencies.load_once_paths.delete(path) end - -ActionView::Base.send :include, WoodpeckersHelper

      vendor/plugins/yaffle/lib/app/helpers/woodpeckers_helper.rb:

      @@ -1381,9 +1118,10 @@ http://www.gnu.org/software/src-highlite -->

      Now your test should be passing, and you should be able to use the Woodpeckers helper in your app.

      -

      9. Add a Custom Route

      +

      8. Routes

      -

      Testing routes in plugins can be complex, especially if the controllers are also in the plugin itself. Jamis Buck showed a great example of this in http://weblog.jamisbuck.org/2006/10/26/monkey-patching-rails-extending-routes-2.

      +

      In a standard routes.rb file you use routes like map.connect or map.resources. You can add your own custom routes from a plugin. This section will describe how to add a custom method called that can be called with map.yaffles.

      +

      Testing routes from plugins is slightly different from testing routes in a standard rails app. To begin, add a test like this:

      vendor/plugins/yaffle/test/routing_test.rb

      private - # yes, I know about assert_recognizes, but it has proven problematic to - # use in these tests, since it uses RouteSet#recognize (which actually - # tries to instantiate the controller) and because it uses an awkward - # parameter order. def assert_recognition(method, path, options) result = ActionController::Routing::Routes.recognize_path(path, :method => method) assert_equal options, result end end
      -

      vendor/plugins/yaffle/init.rb

      +

      Once you see the tests fail by running rake, you can make them pass with:

      +

      vendor/plugins/yaffle/lib/yaffle.rb

      -
      require "routing"
-ActionController::Routing::RouteSet::Mapper.send :include, Yaffle::Routing::MapperExtensions
+
      require "yaffle/routing"
      -

      vendor/plugins/yaffle/lib/routing.rb

      +

      vendor/plugins/yaffle/lib/yaffle/routing.rb

      end end end + +ActionController::Routing::RouteSet::Mapper.send :include, Yaffle::Routing::MapperExtensions

      config/routes.rb

      @@ -1448,143 +1184,725 @@ by Lorenzo Bettini http://www.lorenzobettini.it http://www.gnu.org/software/src-highlite --> 
      ActionController::Routing::Routes.draw do |map|
-  ...
   map.yaffles
 end

      You can also see if your routes work by running rake routes from your app directory.

      -

      10. Odds and ends

      +

      9. Generators

      -

      10.1. Generate RDoc Documentation

      -

      Once your plugin is stable, the tests pass on all database and you are ready to deploy do everyone else a favor and document it! Luckily, writing documentation for your plugin is easy.

      -

      The first step is to update the README file with detailed information about how to use your plugin. A few key things to include are:

      +

      Many plugins ship with generators. When you created the plugin above, you specified the —with-generator option, so you already have the generator stubs in vendor/plugins/yaffle/generators/yaffle.

      +

      Building generators is a complex topic unto itself and this section will cover one small aspect of generators: generating a simple text file.

      +

      9.1. Testing generators

      +

      Many rails plugin authors do not test their generators, however testing generators is quite simple. A typical generator test does the following:

      • -Your name. +Creates a new fake rails root directory that will serve as destination

      • -How to install. +Runs the generator

      • -How to add the functionality to the app (several examples of common use cases). +Asserts that the correct files were generated

      • -Warning, gotchas or tips that might help save users time. +Removes the fake rails root

      -

      Once your README is solid, go through and add rdoc comments to all of the methods that developers will use.

      -

      Before you generate your documentation, be sure to go through and add nodoc comments to those modules and methods that are not important to your users.

      -

      Once your comments are good to go, navigate to your plugin directory and run:

      -
      -
      -
      rake rdoc
      -
      -

      10.2. Write custom Rake tasks in your plugin

      -

      When you created the plugin with the built-in rails generator, it generated a rake file for you in vendor/plugins/yaffle/tasks/yaffle.rake. Any rake task you add here will be available to the app.

      -

      Many plugin authors put all of their rake tasks into a common namespace that is the same as the plugin, like so:

      -

      vendor/plugins/yaffle/tasks/yaffle.rake

      +

      This section will describe how to create a simple generator that adds a file. For the generator in this section, the test could look something like this:

      +

      vendor/plugins/yaffle/test/definition_generator_test.rb

      -
      namespace :yaffle do
-  desc "Prints out the word 'Yaffle'"
-  task :squawk => :environment do
-    puts "squawk!"
+
      require File.dirname(__FILE__) + '/test_helper.rb'
+require 'rails_generator'
+require 'rails_generator/scripts/generate'
+
+class DefinitionGeneratorTest < Test::Unit::TestCase
+
+  def setup
+    FileUtils.mkdir_p(fake_rails_root)
+    @original_files = file_list
+  end
+
+  def teardown
+    FileUtils.rm_r(fake_rails_root)
+  end
+
+  def test_generates_correct_file_name
+    Rails::Generator::Scripts::Generate.new.run(["yaffle_definition"], :destination => fake_rails_root)
+    new_file = (file_list - @original_files).first
+    assert_equal "definition.txt", File.basename(new_file)
+  end
+
+  private
+
+    def fake_rails_root
+      File.join(File.dirname(__FILE__), 'rails_root')
+    end
+
+    def file_list
+      Dir.glob(File.join(fake_rails_root, "*"))
+    end
+
+end
+
      +

      You can run rake from the plugin directory to see this fail. Unless you are doing more advanced generator commands it typically suffices to just test the Generate script, and trust that rails will handle the Destroy and Update commands for you.

      +

      To make it pass, create the generator:

      +

      vendor/plugins/yaffle/generators/yaffle_definition/yaffle_definition_generator.rb

      +
      +
      +
      class YaffleDefinitionGenerator < Rails::Generator::Base
+  def manifest
+    record do |m|
+      m.file "definition.txt", "definition.txt"
+    end
   end
 end
      -

      When you run rake -T from your plugin you will see:

      +

      9.2. The USAGE file

      +

      If you plan to distribute your plugin, developers will expect at least a minimum of documentation. You can add simple documentation to the generator by updating the USAGE file.

      +

      Rails ships with several built-in generators. You can see all of the generators available to you by typing the following at the command line:

      -
      yaffle:squawk             # Prints out the word 'Yaffle'
      +
      ./script/generate
      -

      You can add as many files as you want in the tasks directory, and if they end in .rake Rails will pick them up.

      -

      10.3. Store plugins in alternate locations

      -

      You can store plugins wherever you want - you just have to add those plugins to the plugins path in environment.rb.

      -

      Since the plugin is only loaded after the plugin paths are defined, you can't redefine this in your plugins - but it may be good to now.

      -

      You can even store plugins inside of other plugins for complete plugin madness!

      +

      You should see something like this:

      +
      +
      +
      Installed Generators
+  Plugins (vendor/plugins): yaffle_definition
+  Builtin: controller, integration_test, mailer, migration, model, observer, plugin, resource, scaffold, session_migration
      +
      +

      When you run script/generate yaffle_definition -h you should see the contents of your vendor/plugins/yaffle/generators/yaffle_definition/USAGE.

      +

      For this plugin, update the USAGE file could look like this:

      +
      +
      +
      Description:
+    Adds a file with the definition of a Yaffle to the app's main directory
      +
      +
      +

      10. Generator Commands

      +
      +

      You may have noticed above that you can used one of the built-in rails migration commands migration_template. If your plugin needs to add and remove lines of text from existing files you will need to write your own generator methods.

      +

      This section describes how you you can create your own commands to add and remove a line of text from config/routes.rb.

      +

      To start, add the following test method:

      +

      vendor/plugins/yaffle/test/route_generator_test.rb

      -
      config.plugin_paths << File.join(RAILS_ROOT,"vendor","plugins","yaffle","lib","plugins")
+
      require File.dirname(__FILE__) + '/test_helper.rb'
+require 'rails_generator'
+require 'rails_generator/scripts/generate'
+require 'rails_generator/scripts/destroy'
+
+class RouteGeneratorTest < Test::Unit::TestCase
+
+  def setup
+    FileUtils.mkdir_p(File.join(fake_rails_root, "config"))
+  end
+
+  def teardown
+    FileUtils.rm_r(fake_rails_root)
+  end
+
+  def test_generates_route
+    content = <<-END
+      ActionController::Routing::Routes.draw do |map|
+        map.connect ':controller/:action/:id'
+        map.connect ':controller/:action/:id.:format'
+      end
+    END
+    File.open(routes_path, 'wb') {|f| f.write(content) }
+
+    Rails::Generator::Scripts::Generate.new.run(["yaffle_route"], :destination => fake_rails_root)
+    assert_match /map\.yaffles/, File.read(routes_path)
+  end
+
+  def test_destroys_route
+    content = <<-END
+      ActionController::Routing::Routes.draw do |map|
+        map.yaffles
+        map.connect ':controller/:action/:id'
+        map.connect ':controller/:action/:id.:format'
+      end
+    END
+    File.open(routes_path, 'wb') {|f| f.write(content) }
+
+    Rails::Generator::Scripts::Destroy.new.run(["yaffle_route"], :destination => fake_rails_root)
+    assert_no_match /map\.yaffles/, File.read(routes_path)
+  end
+
+  private
+
+    def fake_rails_root
+      File.join(File.dirname(__FILE__), "rails_root")
+    end
+
+    def routes_path
+      File.join(fake_rails_root, "config", "routes.rb")
+    end
+
+end
      -

      10.4. Create your own Plugin Loaders and Plugin Locators

      -

      If the built-in plugin behavior is inadequate, you can change almost every aspect of the location and loading process. You can write your own plugin locators and plugin loaders, but that's beyond the scope of this tutorial.

      -

      10.5. Use Custom Plugin Generators

      -

      If you are an RSpec fan, you can install the rspec_plugin_generator gem, which will generate the spec folder and database for you. See http://github.com/pat-maddox/rspec-plugin-generator/tree/master.

      -
      -

      11. Appendix

      -
      -

      11.1. References

      -
      -

      11.2. Final plugin directory structure

      -

      The final plugin should have a directory structure that looks something like this:

      +

      Run rake to watch the test fail, then make the test pass add the following:

      +

      vendor/plugins/yaffle/lib/yaffle.rb

      -
      -
        |-- MIT-LICENSE
-  |-- README
-  |-- Rakefile
-  |-- generators
-  |   `-- yaffle
-  |       |-- USAGE
-  |       |-- templates
-  |       |   `-- definition.txt
-  |       `-- yaffle_generator.rb
-  |-- init.rb
-  |-- install.rb
-  |-- lib
-  |   |-- acts_as_yaffle.rb
-  |   |-- commands.rb
-  |   |-- core_ext.rb
-  |   |-- routing.rb
-  |   `-- view_helpers.rb
-  |-- tasks
-  |   `-- yaffle_tasks.rake
-  |-- test
-  |   |-- acts_as_yaffle_test.rb
-  |   |-- core_ext_test.rb
-  |   |-- database.yml
-  |   |-- debug.log
-  |   |-- routing_test.rb
-  |   |-- schema.rb
-  |   |-- test_helper.rb
-  |   `-- view_helpers_test.rb
-  |-- uninstall.rb
-  `-- yaffle_plugin.sqlite3.db
      +
      +
      require "yaffle/commands"
+
      +

      vendor/plugins/yaffle/lib/yaffle/commands.rb

      +
      +
      +
      require 'rails_generator'
+require 'rails_generator/commands'
+
+module Yaffle #:nodoc:
+  module Generator #:nodoc:
+    module Commands #:nodoc:
+      module Create
+        def yaffle_route
+          logger.route "map.yaffle"
+          look_for = 'ActionController::Routing::Routes.draw do |map|'
+          unless options[:pretend]
+            gsub_file('config/routes.rb', /(#{Regexp.escape(look_for)})/mi){|match| "#{match}\n  map.yaffles\n"}
+          end
+        end
+      end
+
+      module Destroy
+        def yaffle_route
+          logger.route "map.yaffle"
+          gsub_file 'config/routes.rb', /\n.+?map\.yaffles/mi, ''
+        end
+      end
+
+      module List
+        def yaffle_route
+        end
+      end
+
+      module Update
+        def yaffle_route
+        end
+      end
+    end
+  end
+end
+
+Rails::Generator::Commands::Create.send   :include,  Yaffle::Generator::Commands::Create
+Rails::Generator::Commands::Destroy.send  :include,  Yaffle::Generator::Commands::Destroy
+Rails::Generator::Commands::List.send     :include,  Yaffle::Generator::Commands::List
+Rails::Generator::Commands::Update.send   :include,  Yaffle::Generator::Commands::Update
+
      +

      vendor/plugins/yaffle/generators/yaffle/yaffle_route_generator.rb

      +
      +
      +
      class YaffleRouteGenerator < Rails::Generator::Base
+  def manifest
+    record do |m|
+      m.yaffle_route
+    end
+  end
+end
+
      +

      To see this work, type:

      +
      +
      +
      ./script/generate yaffle_route
+./script/destroy yaffle_route
      +
      +
      + + + +
      +Note + +
      Editor's note:
      If you haven't set up the custom route from above, script/destroy will fail and you'll have to remove it manually.
      +
      +
      +

      11. Migrations

      +
      +

      If your plugin requires changes to the app's database you will likely want to somehow add migrations. Rails does not include any built-in support for calling migrations from plugins, but you can still make it easy for developers to call migrations from plugins.

      +

      If you have a very simple needs, like creating a table that will always have the same name and columns, then you can use a more simple solution, like creating a custom rake task or method. If your migration needs user input to supply table names or other options, you probably want to opt for generating a migration.

      +

      Let's say you have the following migration in your plugin:

      +

      vendor/plugins/yaffle/lib/db/migrate/20081116181115_create_birdhouses.rb:

      +
      +
      +
      class CreateBirdhouses < ActiveRecord::Migration
+  def self.up
+    create_table :birdhouses, :force => true do |t|
+      t.string :name
+      t.timestamps
+    end
+  end
+
+  def self.down
+    drop_table :birdhouses
+  end
+end
+
      +

      Here are a few possibilities for how to allow developers to use your plugin migrations:

      +

      11.1. Create a custom rake task

      +

      vendor/plugins/yaffle/lib/db/migrate/20081116181115_create_birdhouses.rb:

      +
      +
      +
      class CreateBirdhouses < ActiveRecord::Migration
+  def self.up
+    create_table :birdhouses, :force => true do |t|
+      t.string :name
+      t.timestamps
+    end
+  end
+
+  def self.down
+    drop_table :birdhouses
+  end
+end
+
      +

      vendor/plugins/yaffle/tasks/yaffle.rake:

      +
      +
      +
      namespace :db do
+  namespace :migrate do
+    desc "Migrate the database through scripts in vendor/plugins/yaffle/lib/db/migrate and update db/schema.rb by invoking db:schema:dump. Target specific version with VERSION=x. Turn off output with VERBOSE=false."
+    task :yaffle => :environment do
+      ActiveRecord::Migration.verbose = ENV["VERBOSE"] ? ENV["VERBOSE"] == "true" : true
+      ActiveRecord::Migrator.migrate("vendor/plugins/yaffle/lib/db/migrate/", ENV["VERSION"] ? ENV["VERSION"].to_i : nil)
+      Rake::Task["db:schema:dump"].invoke if ActiveRecord::Base.schema_format == :ruby
+    end
+  end
+end
+
      +

      11.2. Call migrations directly

      +

      vendor/plugins/yaffle/lib/yaffle.rb:

      +
      +
      +
      Dir.glob(File.join(File.dirname(__FILE__), "db", "migrate", "*")).each do |file|
+  require file
+end
+
      +

      db/migrate/20081116181115_create_birdhouses.rb:

      +
      +
      +
      class CreateBirdhouses < ActiveRecord::Migration
+  def self.up
+    Yaffle::CreateBirdhouses.up
+  end
+
+  def self.down
+    Yaffle::CreateBirdhouses.down
+  end
+end
+
      +
      + + + +
      +Note + +
      Editor's note:
      several plugin frameworks such as Desert and Engines provide more advanced plugin functionality.
      +
      +

      11.3. Generate migrations

      +

      Generating migrations has several advantages over other methods. Namely, you can allow other developers to more easily customize the migration. The flow looks like this:

      +
        +
      • +

        +call your script/generate script and pass in whatever options they need +

        +
        • +
      • +

        +examine the generated migration, adding/removing columns or other options as necessary +

        +
        • +
      +

      This example will demonstrate how to use one of the built-in generator methods named migration_template to create a migration file. Extending the rails migration generator requires a somewhat intimate knowledge of the migration generator internals, so it's best to write a test first:

      +

      vendor/plugins/yaffle/test/yaffle_migration_generator_test.rb

      +
      +
      +
      require File.dirname(__FILE__) + '/test_helper.rb'
+require 'rails_generator'
+require 'rails_generator/scripts/generate'
+
+class MigrationGeneratorTest < Test::Unit::TestCase
+
+  def setup
+    FileUtils.mkdir_p(fake_rails_root)
+    @original_files = file_list
+  end
+
+  def teardown
+    ActiveRecord::Base.pluralize_table_names = true
+    FileUtils.rm_r(fake_rails_root)
+  end
+
+  def test_generates_correct_file_name
+    Rails::Generator::Scripts::Generate.new.run(["yaffle_migration", "some_name_nobody_is_likely_to_ever_use_in_a_real_migration"], :destination => fake_rails_root)
+    new_file = (file_list - @original_files).first
+    assert_match /add_yaffle_fields_to_some_name_nobody_is_likely_to_ever_use_in_a_real_migrations/, new_file
+    assert_match /add_column :some_name_nobody_is_likely_to_ever_use_in_a_real_migrations do |t|/, File.read(new_file)
+  end
+
+  def test_pluralizes_properly
+    ActiveRecord::Base.pluralize_table_names = false
+    Rails::Generator::Scripts::Generate.new.run(["yaffle_migration", "some_name_nobody_is_likely_to_ever_use_in_a_real_migration"], :destination => fake_rails_root)
+    new_file = (file_list - @original_files).first
+    assert_match /add_yaffle_fields_to_some_name_nobody_is_likely_to_ever_use_in_a_real_migration/, new_file
+    assert_match /add_column :some_name_nobody_is_likely_to_ever_use_in_a_real_migration do |t|/, File.read(new_file)
+  end
+
+  private
+    def fake_rails_root
+      File.join(File.dirname(__FILE__), 'rails_root')
+    end
+
+    def file_list
+      Dir.glob(File.join(fake_rails_root, "db", "migrate", "*"))
+    end
+
+end
+
      +
      + + + +
      +Note + +
      Editor's note:
      the migration generator checks to see if a migation already exists, and it's hard-coded to check the db/migrate directory. As a result, if your test tries to generate a migration that already exists in the app, it will fail. The easy workaround is to make sure that the name you generate in your test is very unlikely to actually appear in the app.
      +
      +

      After running the test with rake you can make it pass with:

      +

      vendor/plugins/yaffle/generators/yaffle/yaffle_generator.rb

      +
      +
      +
      class YaffleMigrationGenerator < Rails::Generator::NamedBase
+  def manifest
+    record do |m|
+      m.migration_template 'migration:migration.rb', "db/migrate", {:assigns => yaffle_local_assigns,
+        :migration_file_name => "add_yaffle_fields_to_#{custom_file_name}"
+      }
+    end
+  end
+
+  private
+    def custom_file_name
+      custom_name = class_name.underscore.downcase
+      custom_name = custom_name.pluralize if ActiveRecord::Base.pluralize_table_names
+      custom_name
+    end
+
+    def yaffle_local_assigns
+      returning(assigns = {}) do
+        assigns[:migration_action] = "add"
+        assigns[:class_name] = "add_yaffle_fields_to_#{custom_file_name}"
+        assigns[:table_name] = custom_file_name
+        assigns[:attributes] = [Rails::Generator::GeneratedAttribute.new("last_squawk", "string")]
+      end
+    end
+end
+
      +

      The generator creates a new file in db/migrate with a timestamp and an add_column statement. It reuses the built in rails migration_template method, and reuses the built-in rails migration template.

      +

      It's courteous to check to see if table names are being pluralized whenever you create a generator that needs to be aware of table names. This way people using your generator won't have to manually change the generated files if they've turned pluralization off.

      +

      To run the generator, type the following at the command line:

      +
      +
      +
      ./script/generate yaffle_migration bird
      +
      +

      and you will see a new file:

      +

      db/migrate/20080529225649_add_yaffle_fields_to_birds.rb

      +
      +
      +
      class AddYaffleFieldsToBirds < ActiveRecord::Migration
+  def self.up
+    add_column :birds, :last_squawk, :string
+  end
+
+  def self.down
+    remove_column :birds, :last_squawk
+  end
+end
+
      +
      +

      12. Rake tasks

      +
      +

      When you created the plugin with the built-in rails generator, it generated a rake file for you in vendor/plugins/yaffle/tasks/yaffle.rake. Any rake task you add here will be available to the app.

      +

      Many plugin authors put all of their rake tasks into a common namespace that is the same as the plugin, like so:

      +

      vendor/plugins/yaffle/tasks/yaffle.rake

      +
      +
      +
      namespace :yaffle do
+  desc "Prints out the word 'Yaffle'"
+  task :squawk => :environment do
+    puts "squawk!"
+  end
+end
+
      +

      When you run rake -T from your plugin you will see:

      +
      +
      +
      yaffle:squawk             # Prints out the word 'Yaffle'
      +
      +

      You can add as many files as you want in the tasks directory, and if they end in .rake Rails will pick them up.

      +

      Note that tasks from vendor/plugins/yaffle/Rakefile are not available to the main app.

      +
      +

      13. PluginGems

      +
      +

      Turning your rails plugin into a gem is a simple and straightforward task. This section will cover how to turn your plugin into a gem. It will not cover how to distribute that gem.

      +

      Historically rails plugins loaded the plugin's init.rb file. In fact some plugins contain all of their code in that one file. To be compatible with plugins, init.rb was moved to rails/init.rb.

      +

      It's common practice to put any developer-centric rake tasks (such as tests, rdoc and gem package tasks) in Rakefile. A rake task that packages the gem might look like this:

      +

      vendor/plugins/yaffle/Rakefile:

      +
      +
      +
      PKG_FILES = FileList[
+  '[a-zA-Z]*',
+  'generators/**/*',
+  'lib/**/*',
+  'rails/**/*',
+  'tasks/**/*',
+  'test/**/*'
+]
+
+spec = Gem::Specification.new do |s|
+  s.name = "yaffle"
+  s.version = "0.0.1"
+  s.author = "Gleeful Yaffler"
+  s.email = "yaffle@example.com"
+  s.homepage = "http://yafflers.example.com/"
+  s.platform = Gem::Platform::RUBY
+  s.summary = "Sharing Yaffle Goodness"
+  s.files = PKG_FILES.to_a
+  s.require_path = "lib"
+  s.has_rdoc = false
+  s.extra_rdoc_files = ["README"]
+end
+
+desc 'Turn this plugin into a gem.'
+Rake::GemPackageTask.new(spec) do |pkg|
+  pkg.gem_spec = spec
+end
+
      +

      To build and install the gem locally, run the following commands:

      +
      +
      +
      cd vendor/plugins/yaffle
+rake gem
+sudo gem install pkg/yaffle-0.0.1.gem
      +
      +

      To test this, create a new rails app, add config.gem "yaffle" to environment.rb and all of your plugin's functionality will be available to you.

      +
      +

      14. RDoc Documentation

      +
      +

      Once your plugin is stable and you are ready to deploy do everyone else a favor and document it! Luckily, writing documentation for your plugin is easy.

      +

      The first step is to update the README file with detailed information about how to use your plugin. A few key things to include are:

      +
        +
      • +

        +Your name +

        +
        • +
      • +

        +How to install +

        +
        • +
      • +

        +How to add the functionality to the app (several examples of common use cases) +

        +
        • +
      • +

        +Warning, gotchas or tips that might help save users time +

        +
        • +
      +

      Once your README is solid, go through and add rdoc comments to all of the methods that developers will use. It's also customary to add #:nodoc: comments to those parts of the code that are not part of the public api.

      +

      Once your comments are good to go, navigate to your plugin directory and run:

      +
      +
      +
      rake rdoc
      +
      +
      +

      15. Appendix

      +
      +

      If you prefer to use RSpec instead of Test::Unit, you may be interested in the RSpec Plugin Generator.

      +

      15.1. References

      +
      +

      15.2. Contents of lib/yaffle.rb

      +

      vendor/plugins/yaffle/lib/yaffle.rb:

      +
      +
      +
      require "yaffle/core_ext"
+require "yaffle/acts_as_yaffle"
+require "yaffle/commands"
+require "yaffle/routing"
+
+%w{ models controllers helpers }.each do |dir|
+  path = File.join(File.dirname(__FILE__), 'app', dir)
+  $LOAD_PATH << path
+  ActiveSupport::Dependencies.load_paths << path
+  ActiveSupport::Dependencies.load_once_paths.delete(path)
+end
+
+# optionally:
+# Dir.glob(File.join(File.dirname(__FILE__), "db", "migrate", "*")).each do |file|
+#   require file
+# end
+
+
      +

      15.3. Final plugin directory structure

      +

      The final plugin should have a directory structure that looks something like this:

      +
      +
      +
      |-- MIT-LICENSE
+|-- README
+|-- Rakefile
+|-- generators
+|   |-- yaffle_definition
+|   |   |-- USAGE
+|   |   |-- templates
+|   |   |   `-- definition.txt
+|   |   `-- yaffle_definition_generator.rb
+|   |-- yaffle_migration
+|   |   |-- USAGE
+|   |   |-- templates
+|   |   `-- yaffle_migration_generator.rb
+|   `-- yaffle_route
+|       |-- USAGE
+|       |-- templates
+|       `-- yaffle_route_generator.rb
+|-- install.rb
+|-- lib
+|   |-- app
+|   |   |-- controllers
+|   |   |   `-- woodpeckers_controller.rb
+|   |   |-- helpers
+|   |   |   `-- woodpeckers_helper.rb
+|   |   `-- models
+|   |       `-- woodpecker.rb
+|   |-- db
+|   |   `-- migrate
+|   |       `-- 20081116181115_create_birdhouses.rb
+|   |-- yaffle
+|   |   |-- acts_as_yaffle.rb
+|   |   |-- commands.rb
+|   |   |-- core_ext.rb
+|   |   `-- routing.rb
+|   `-- yaffle.rb
+|-- pkg
+|   `-- yaffle-0.0.1.gem
+|-- rails
+|   `-- init.rb
+|-- tasks
+|   `-- yaffle_tasks.rake
+|-- test
+|   |-- acts_as_yaffle_test.rb
+|   |-- core_ext_test.rb
+|   |-- database.yml
+|   |-- debug.log
+|   |-- definition_generator_test.rb
+|   |-- migration_generator_test.rb
+|   |-- route_generator_test.rb
+|   |-- routes_test.rb
+|   |-- schema.rb
+|   |-- test_helper.rb
+|   |-- woodpecker_test.rb
+|   |-- woodpeckers_controller_test.rb
+|   |-- wookpeckers_helper_test.rb
+|   |-- yaffle_plugin.sqlite3.db
+|   `-- yaffle_test.rb
+`-- uninstall.rb
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